The appearance before reporters capped off Trump’s two-day visit to England. On Wednesday, Trump spent a pomp-filled day at the British royal family’s castle in Windsor.

President Donald Trump has suggested he’s working to reestablish a U.S. presence at Bagram Air Base in Afghanistan.

British officials have festooned the trip with the kind of superlatives Trump revels in: It’s an “unprecedented” second state visit for the U.S. leader, featuring the biggest military honor guard eve...